Disease relevance of MED8

• To determine whether the p27 protein represents the Med8 product, we expressed MED8 gene in E. coli and demonstrated that the heterologous synthesized protein specifically binds to both UASSUC2 and DRS2HXK2 [1].

High impact information on MED8

• As part of our effort to understand the functions of Elongin BC-based ubiquitin ligases, we exploited a modified yeast two-hybrid screen to identify a mammalian BC-box protein similar in sequence to Saccharomyces cerevisiae Mediator subunit Med8p [2].
• Taken together, these results suggest that assembly of Mediator is a multistep process that involves conversion of both Med4 and Med8 to their low mobility forms [3].
• Because this site was previously involved in the Hxk2p-dependent glucose-induced regulation of gene transcription, we tested whether Hxk2p interacts with Med8p [4].
• Mediator factor Med8p interacts with the hexokinase 2: implication in the glucose signalling pathway of Saccharomyces cerevisiae [4].
• The amino terminal sequence of p27 identified the MED8 gene (open reading frame YBR193C), located in chromosome II of S. cerevisiae, as the gene coding for the protein [1].

Biological context of MED8

• We conclude that Hxk2p operates through the MED8 site, by interacting with Med8p, in the glucose signal transduction pathway of Saccharomyces cerevisiae [4].
• Atomic force microscopy has allowed for direct visualization of Med8 interactions with a 305 bp fragment of SUC2 promoter and with a 676 bp fragment of HXK2 gene, containing respectively the UASs and DRSs regulatory regions [5].
• A new essential gene, YBR1403, has been identified by disruption; it possesses a leucine zipper motif [6].
• The deduced amino acid sequence of the Sep15 protein shows significant homology to Med8, a component of the Saccharomyces cerevisiae transcription mediator complex [7].
• The main regulatory mechanism that controls the HXK2 gene expression in yeast is mediated by the Rgt1 and Med8 transcription factors, which repress HXK2 expression in low-glucose containing media [8].

Other interactions of MED8

• Two-hybrid and chromatin immunoprecipitation experiments indicate that an Snf1-dependent interaction between Rgt1 and Med8 in the repressor complex is also essential for Rgt1 repression [8].

References